Design and Synthesis of a Series of CL-20 Cocrystals: Six-Membered Symmetrical N-Heterocyclic Compounds as Effective Coformers

Abstract

Cocrystallization of energetic compounds has recently been considered as an effective method to adjust the properties through the selection of coformers, particularly to improve the detonation properties and reduce the mechanical sensitivity of CL-20. In this research, a reliable and promising design strategy to synthesize CL-20-based cocrystals was presented, where (i) the coformer should show local structural similarity to CL-20, i.e., fiveor sixmembered symmetric heterocycles, and (ii) the molecular structure of the coformer should contain electron-donating groups. In order to verify the adaptability of this design strategy, pyrazine, 2,6-dimethoxy-3,5-dinitropyrazine, and 2,5-dimethylpyrazine were selected as the templates of six-membered symmetrical N-heterocyclic compounds for cocrystallization with CL-20. Fortunately, on the basis of the results of the experiments and the crystal analysis, three compounds were successfully cocrystallized with CL-20. Moreover, two cocrystals with the same components and different stoichiometric ratios were formed by pyrazine and CL-20. In addition, the properties of the designed cocrystals, including thermal stability, detonation properties, and sensitivities, were also studied in detail. Cocrystallization of CL-20 with the aforementioned coformers demonstrates the appropriateness of six-membered symmetrical N-heterocyclic compounds as coformers. In light of this finding, the safety and detonation properties of CL-20 can be modulated by employing suitable six-membered N-heterocyclic compounds as coformers.

Exploring the effects of solvents on an organic explosive: Insights from the electron structure, electrostatic potential, and conformational transformations of 2,4,6,8,10,12‐hexanitro‐2,4,6,8,10,12‐hexaazaisowurtzitane

“…Researchers have already prepared many CL‐20‐based cocrystals in solution . The above molecular conformers of CL‐20 have all been observed in CL‐20‐based cocrystals in ambient conditions; the γ ‐form and the β ‐form were the most common conformers of the reported CL‐20 cocrystals. As CL‐20 is a polymorphic molecule, the mechanism of its conformational transformation in solvents is quite complicated, and the influence of solvents still requires further study.…”

1,3,4‐Oxadiazole Bridges: A Strategy to Improve Energetics at the Molecular Level

“…[1][2][3][4] As aresult, current research is focused on improving the stability, especially mechanical and thermal stabilities of these energetic materials.M odifications at the interface (cladding and mixing) and crystal levels (co-crystal and host-guest assembly) of HMX and CL-20 have been reported several times. [5][6][7][8][9] Along with the refinement of classical high-energy explosives, studies on new high energy density materials are under way focusing on the synthesis of five-or six-ring heterocyclic systems (including furazan, tetrazine,t etrazole and triazole) because of their high-energy content and green explosion products. [10][11][12][13] With ac ombination of various energetic rings and groups,t hese compounds are expected to exhibit excellent performance and moderate sensitivity.…”

Understanding the aqueous chemistry of quinoline and the diazanaphthalenes: insight from DFT study

“…The agrochemical, pharmaceutical, corrosion and vertinary industries are few of the vast application fields for heterocyclic compounds (HCs) [ 1 , 2 , 3 , 4 ]. In other to expand the domain of consumption of heterocyclic compounds and its derivatives, much energy have been channeled into the development [ 2 ], synthesis [ 2 , 3 , 4 , 5 , 6 , 7 , 8 , 9 , 10 , 11 , 12 ] and interaction studies of these compounds [ 13 , 14 , 15 ] in various solvent systems. Many important organic-based chemical industries utilizes HCs as their feedstock, for special and multipurpose chemicals manufacture.…”